(i) Field of the Invention
This invention relates to sebum secretion accelerators and more particularly, to sebum secretion accelerator compositions comprising cholesteryl esters of branched fatty acids in high concentrations.
(ii) Description of the Prior Art
For the purpose of nutrition and beauty cares for skin, it is usual to apply cosmetics containing suitable lipids and water to skin. By the application, the protective film of the cosmetic is formed on the surface of the skin, thereby preventing evaporation of water and retaining a suitable degree of lipid on the skin surface. As a result, the skin is kept smooth and soft. These types of cosmetics are ordinarily employed skin lotions or cosmetics.
As is known in the art, healthy and beautiful skin is originally derived from normal secretion of sebum. With human body, the secretion of sebum is vigorous at the growing stage and is gradually reduced at the adult stage. This is more remarkable at senescence. It is generally accepted that women are less active than men with regard to the secretion of sebum. According to Greene et al, the legs are the least among parts of the body with regard to the amount of the secretion, and the amount is about one eightieth of the forehead whose amount of the secretion is the highest. In this connection, within the parts of the face, secretion in cheeks is about one third of that in the forehead. The skin at the parts where the amount of the secretion is small has the tendency toward drying [R. S. Greene et al; J. Invest. Dermatol., 54, 240 (1970)]. Accordingly, in order to exercise beauty cares for the skin of women of the middle or older ages whose amount of sebum secretion lowers, it is the most natural and favorable to cause the secretion of sebum to be promoted. However, conventional cosmetics do not serve to beautify the skin by promoting the secretion of sebum of the human body, thus not contributing to the substantial beautification of the skin. For treatment of dried and roughened skin, to accelerate the secretion from the skin brings about a great effect. Especially, the acceleration of the secretion of sebum is useful in improving efflorescence such as xerodermia, atopic dermatitis or the like and preventing exacerbation.
Known substances having the action of accelerating the sebum secretion include .gamma.-oryzanol, pantetheine and fatty acid esters and the like. However, .gamma.-oryzanol which is cholesterol bonded with ferulic acid through ester bonding has a melting point as high as 127.degree. to 135.degree. C. and cannot be added in high concentrations, thus it being difficult to make preparations. Pantetheine-fatty acid esters (Japanese Laid-open Application Nos. 54-160315 and 54-160751) are solid at room temperature with a difficulty in preparation.